1. Technical Field
These inventions relate, generally, to apparatus and methods used in well servicing, such as oil and gas wells. More specifically, the inventions relate to downhole apparatus which when assembled in a tubing string can repeatedly and selectively create a fluid bypass in the circulating system of a well being serviced.
2. Background Art
As is known in the relevant art, bypass tools are typically run into wellbores assembled or connected in a tubular string and are utilized to selectively discharge fluids from the interior of the tubing string into the annular space around the tool. In some applications, this discharge is used to boost or assist the flow of debris in the annulus.
As used herein, the words “comprise,” “have,” “include,” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that do not exclude additional elements or steps. The term “wellbore” refers to the subterranean well opening, including cased and uncased. The term “tubing string” is used generically to refer to tubular members positioned in a wellbore, such as drill pipe, tubing and the like. The term “well fluids” refers broadly to any fluids found in a wellbore. As used in this application, the term “bypass” refers to a fluid flow path from the bore or interior of a tubing string into the wellbore/tubing string annulus, at some point along the length of the tubing string, rather than out the lower most end of the tubing string and downhole assembly. It is understood that even in a bypass mode, some fluid may still traverse the length of the tubing string and exit the lowermost end thereof. As used herein, “weight down” is used to describe a condition of the tubing string where at least a portion of the weight of the tubing string is supported downhole in compression rather than tension. As used herein, the term “poppet valve” is used to refer to a valve operated by springs or the like that plugs and unplugs its openings by axial movement.